Lens for photographic and like purposes



D D d U I aw a Aug. 27, 1935. H. w. LEE

LENS FOR PHOTOGRAPHIC AND LIKE PURPOSES Filed July 20, 19:54

2 R4 6 8 IO INVENTOR BY z E C ATTokNEY Patented Aug. 27, 1935 2,012,822

UNITED STATES PATENT OFFICE LENS FOR PHOTOGRAPHIC AND LIKE PURPOSES Horace William Lee, Leicester, England, assignor to Kapella Limited, Leicester, England, a corporation of England Application July 20, 1934, Serial No. 736,161 In Great Britain July 22, 1933 14 Claims. (Cl. 88-57) This invention relates to lenses for photograto this invention, is that I am thereby enabled, phy and the like, of the kind comprising a diswhile maintaining good correction for axial and persive member between two collective members, oblique aberrations, to use, in the dispersive and one of its objects is to provide lenses well cormember, curves of such radius that I can attain rected for axial and oblique aberrations and of an aperture as large as f/I, and this feature of larger aperture than hitherto. my invention may be extended so as to attain Three suitable forms of lens systems embodyeven larger apertures by using three, or even ing the present improvement are illustrated, by more, such meniscus lenses in this collective memway of example, in the accompanying drawing, ber, and adjusting accordingly the curvatures of wherein: the dispersive member. m Fig. 1 is a longitudinal section through a five- In every case, the collective menisci are preferelement lens system; ably such that the ratio of the powers of any two Fig. 2 is a longitudinal section through a sixdoes not exceed the value two, and the sum of element lens system; and their powers amounts to at least half, but does Fig. 3 is a longitudinal section through a sevnot exceed three-fourths, that of the system. 15 en-element lens system. Also, the convex surfaces of such meniscus collec- In this specification, I mean by: tive components are preferably of successively A system.-The complete lens system. greater radius in order counting from the dis- A member.A separate portion of a system, Persive membergenerally having a distinct, though not always It is obvious that any of the collective menisci 2o entirely separate, function. could be compounded without departing from the A component-A constituent part of a memspirit of this invention. ber, either a single lens element or two or more The third member is constituted by either 8- elements in surface contact, generally cemented single collective component, which may be either together. single or compound, a plurality of such elements, 25

Element.-A single uncompounded lens, or comprises a single collective element outside In lens systems constructed according to the a dispersive component which may be single or invention, the dispersive member is constituted p dby a compound dispersive meniscus component, One advantage of ma t c e t ve preferably comprising a double convex element her, which is on the concave side of the dispersive of relatively high refractive index, in contact member, as a single element is that there is less with, or close to, a double concave element of liability to flare. Alternatively, by dividing this higher refractive index, the difierence of index into two components, I am the better enabled to being not substantially less than 0.07. perfect the zonal correction, and by compounding The dispersive member has the ratio of the at least one of these components, I am the better power of its outer convex surface to that of the enabled to improve the flatness of field and/or system not substantially less than the ratio of the oblique aberrations. the focal length to the diameter of the entrance I now give data for the construction of three pupil. lenses of unit equivalent focal length according The dispersive member preferably has a thickto my invention, illustrated in the accompany- 40 ness greater than one-quarter of the focal length ing drawing. The notation is that the succesof the system. sive radii of curvature, counting from the front, On the convex side of said dispersive member are called R1, R2, etc., the sign denoting that is a collective member comprising a plurality of the curve is convex toward the incident light, meniscus collective components with their conand-that it is concave toward the same. The 45 cave surfaces turned toward the dispersive memaxial thicknesses of the elements are denoted by bar, D1, D2, etc., and the separations of the compo- The advantage of employing a plurality of nents by S1, S2, etc. meniscus lenses in the collective member on the The material is defined in terms of the mean convex side of the dispersive member, according refractive index no, as conventionally employed,

followed by the Abbe V number and by the type number in Messrs. Chance Brothers optical glass catalogue.

Example 1.--Aperture f/1 (Figure 1) Radii Thickness Separation D V No.

ltd-1.2147

D1 .0881 1.6135 59. 4 8065 Rat-3.107

Si .005 Ra+. 7327 D2 .0838 l. 6135 59. 4 8065 R4+1J355 D3 .337 1.6062 59.8 4317 li -1.0516

D5 1372 1. 6135 59. 4 8065 Ra1.9062

Example 2.Aperture f/1 (Figure 2) Radli Thickness Separation "D V N o.

D .0881 1.6135 59.4 8065 Rz+3.107

S1 005 RH". 7327 D2 .0838 1.6135 59.4 8065 R4+l. 1855 D: .337 1. 6062 59.8 4317 Ra-l. 0516 S: 2294 Ra-H. 19

D .065 1.6135 59.4 8065 R. Q

S4 005 R c-i. 72

Do .075 1.6135 59.4 $065 n m Example 3.Aperture f/1.1 (Figure 3) Radii Thickness Separation "D V No.

D1 .065 1.6135 59.4 8065 Rz+3. 13

D: .065 1.6135 59.4 8065 RH-l. 23

S: 25 Ills-.42

DI .20 1.6437 48.3 Rio-.52

SI 005 n+- 8 D1 .10 1.6437 48.3 Bis-2. 09

not yet in Messrs. Chance Brothers collective components with their convex sides toward the incident light, said dispersive member comprising a double convex element of relatively high refractive index, and a double concave element having a refractive index not greatly less than that of said convex element, the ratio of the power of the front convex surface of said dispersive member to the power of the whole system being not substantially less than the ratio of the equivalent focal length to the diameter of the entrance pupil.

2. A lens system as in claim 1, in which the said double concave element has a refractive index at least 0.07 higher than that of said double convex element.

3. A lens system as in claim 1, in which the thickness of said dispersive member is greater than one-quarter of the focal length of the system as a whole.

4. A lens system comprising a dispersive compound two-element meniscus member with its convex side toward the incident light arranged between two collective members, whereof that on the convex side of said dispersive member comprises a plurality of meniscus collective components with their convex sides toward the incident light, and the facing surfaces of the two elements of the compound meniscus member are strongly curved and concave toward the incident light.

5. A lens system as in claim 4, in which said facing surfaces have a radius of the order of magnitude of the focal length of the lens system as a whole.

6. A lens system as in claim 1, in which the convex surfaces of the said collective components are of successively greater radius in order counting from the dispersive member.

7. A lens system, comprising an outer collective member comprising a plurality of meniscus collective components with their convex sides toward the incident light, an intermediate dispersing two-element compound meniscus member with its convex side toward the incident light, the contacting or adjacent surfaces of the two elements being strongly curved and concave toward the incident light, and an inner collective member, the radii of the convex surfaces of the said components and the said compound meniscus member decreasing progressively from the outermost surface of the lens system inwardly.

8. A lens system as in claim 1, in which the ratio of the powers of any two of the collective meniscus components constituting the member on the convex side of the dispersive member does not exceed the value two.

9. A lens system as in claim 1, in which the collective member on the concave side of the dispersive meniscus component is a single element.

10. A lens system as in claim 1, in which the collective member on the concave side of the dispersive member comprises a plurality of separated collective components.

11. A lens system comprising a single dispersive compound meniscus member with its convex side toward the incident light arranged between two collective members, whereof that on the convex side of said dispersive member comprises a plurality of meniscus collective components with their concave surfaces turned toward the dispersive member.

12. A lens system comprising a single dispersive compound meniscus member with its convex side toward the incident light arranged between two or more collective members, the dispersive meniscus member comprising a double convex element of relatively high refractive index and a double concave element of higher refractive index, the difference of index being not substantially less than 0.07. and having the ratio of the power of its outer convex surface to that of the whole system not substantially less than the ratio of the equivalent focal length to the diameter of the entrance pupil.

13. A lens system as in claim 12, in which the thickness of said dispersive member is greater than one-quarter of the focal length of the system as a whole.

14. A lens system comprising a dispersive meniscus member having a thickness greater than one-quarter of the focal length of the lens system as a whole, arranged with its convex side toward the incident light and located between two collective members, whereof that on the convex side of said dispersive member comprises a plurality of meniscus collective components with their convex sides toward the incident light, said dispersive member comprising a double convex element of relatively high refractive index, and a double concave element having a refractive index not greatly less than that of said convex element, the contacting or adjacent surfaces of said elements being strongly curved and concave toward the incident light, the ratio of the power of the front convex surface of said dispersive member to the power of the whole system being not substantially less than the ratio of the equivalent focal length to the diameter of the entrance pupil.

HORACE WILLIAM LEE.

ti an-. 1. 

